My objectives are to investigate the molecular architecture of the nuclear envelope lamina and the nuclear pore complex, to determine how these components of the nuclear envelope are related to its characteristic structural features and principal functions. The nuclear lamina is believed to provide a structural framework for the nuclear envelope, and contains primarily a polymer of three discrete polypeptides. Using biochemical, cell fractionation, and electron microscopic procedures, I will analyze the molecular organization and subunit structure of the lamina polymer, and will investigate how this polymeric assembly is attached to the inner nuclear membrane. Furthermore, I will study the biochemical mechanism for the reversible depolymerization of the lamina during cell division, which is believed to play a central role in the reversible mitotic disassembly of the nuclear envelope. Nuclear pore complexes are ultrastructurally complex protein assemblies that are involved in nucleocytoplasmic transport of various molecules, including RNA. With biochemical and electron microscopic antibody labelling techniques, I will identify a set of the major polypeptides of the pore complex. In addition, I will endeavor to subfractionate nuclear envelopes to purify structural subunits of the pore complex containing functionally-associated polypeptides. I will also purify the major ATPase enzymes of the pore complex, as single proteins and as components of oligomeric pore complex substructures. These investigations will provide a framework for future studies on how the pore complex accomplishes active macromolecular transport.